Heterojunction bipolar transistors (HBTs) are generally utilized in power applications as well as in applications that require the active devices to have low 1/f noise and good high frequency performance. Typical examples are low noise oscillation circuits. This choice of utilizing HBTs for low noise applications results because HBTs are vertical devices with minimal exposed surface area, thus suffering less degradation due to surface-related noise sources, contrary to the case of Field Effect Transistors (FETs). While HBTs have consistently demonstrated lower 1/f noise than FET devices, conventional HBTs are still not totally free from surface-related noise sources. In HBTs fabricated with conventional process techniques, the extrinsic base surfaces, which are generally formed of GaAs, are exposed to air. Since a free GaAs surface is characterized by a high surface recombination velocity, significant surface recombination occurs in these extrinsic base surfaces. Fortunately, a surface passivation technique using a depleted AlGaAs layer on top of the extrinsic base can be applied to reduce this surface recombination and this technique has been utilized in the prior art. To date, this surface passivation technique has been limited to the case of using AlGaAs as the emitter material. However, because AlGaAs is known to have substantial DX bulk recombination centers, AlGaAs/GaAs HBTs naturally suffer some degradation in noise performance. DX centers are donor related deep levels in AlGaAs exhibiting unusual and complex properties, such as persistent photoconductivity. DX centers behave as effective electron traps. The current transients caused by the capture and emission of electrons at DX centers constitute noise.